地震计线性误差精确测试     

王洪体  崔仁胜  李江  叶鹏  林湛 《地震地磁观测与研究》2018,39(2):173-177

利用同步测试标准地震数据采集器标定电流的地震计线性误差测试方法，避免了标定信号输出电流波动对地震计线性误差测试的影响，按DB/T 21—2007规定的方法进行数据处理，并判定结果是否符合DB/T 22—2007的要求。实际测试表明，该方法测试精度可以达到0.000 5%，满足测试线性偏差小于0.01%的需要，且操作简单，无额外设备要求，可行性高，可在固定地震台站、野外等条件下使用，具有较大的应用价值。  相似文献   

A comparison of the effectiveness of the roots of two grass species in reducing soil erosion on alluvial fans in south-east China     

Fangshi Jiang  Kaiwen He  Jiahui Lin  Hui Li  Zhenzhi Zhan  Jinshi Lin  Hongli Ge  Ming Kuang Wang  Yanhe Huang 《水文研究》2020,34(1):96-110

The effects of root systems on soil detachment by overland flow are closely related to vegetation types. The objective of this study was to quantify the effects of two gramineous roots (Paspalum mandiocanum with shallow roots and Pennisetum giganteum with deep roots) on soil detachment capacity, rill erodibility, and critical shear stress on alluvial fans of benggang in south-east China. A 4-m-long and 0.12-m-wide flume was used. Slope steepness ranged from 9% to 27%, and unit flow discharge ranged from 1.39 × 10⁻³ to 4.19 × 10⁻³ m² s⁻¹. The mean detachment capacities of P. mandiocanum and P. giganteum lands were 18% and 38% lower than that of bare land, respectively, and the effects of root on reducing soil detachment were mainly reflected in the 0- to 5-cm soil layer. The most important factors in characterizing soil detachment capacity were root length density and soil cohesion, and soil detachment capacity of the two grass lands could be estimated using flow shear stress, soil cohesion, and root length density (NSE = 0.90). With the increase in soil depth, rill erodibility increased, whereas shear stress decreased. The mean rill erodibilities of P. mandiocanum and P. giganteum lands were 81% and 61% as much as that of bare land, respectively. Additionally, rill erodibilities of the two grass lands could be estimated as an exponential function by root length density and soil cohesion (NSE = 0.88). The mean critical shear stress of P. mandiocanum and P. giganteum lands was 1.29 and 1.39 times that of bare land, respectively, and it could be estimated with a linear function by root length density (NSE = 0.76). This study demonstrated that planting of the two grasses P. mandiocanum and P. giganteum could effectively reduce soil detachment and enhance soil resistance to erosion on alluvial fans, with the deep roots of P. giganteum being more effective than the shallow roots of P. mandiocanum. The results are helpful for understanding the influencing mechanism of root systems on soil detachment process.  相似文献   

New graphical methods for estimating aquifer hydraulic parameters using pumping tests with exponentially decreasing rates     

Chao Zhuang  Zhifang Zhou  Hongbin Zhan  Jinguo Wang  Yabing Li  Zhi Dou 《水文研究》2019,33(17):2314-2322

Actual pumping tests may involve continuously decreasing rates over a certain period of time, and the hydraulic conductivity (K) and specific storage (S_s) of the tested confined aquifer cannot be interpreted from the classical constant‐rate test model. In this study, we revisit the aquifer drawdown characteristics of a pumping test with an exponentially decreasing rate using the dimensionless analytical solution for such a variable‐rate model. The drawdown may decrease with time for a short period of time at intermediate pumping times for such pumping tests. A larger ratio of initial to final pumping rate and a smaller radial distance of the observation well will enhance the decreasing feature. A larger decay constant results in an earlier decrease, but it weakens the extent of such a decrease. Based on the proposed dimensionless transformation, we have proposed two graphical methods for estimating K and S_s of the tested aquifer. The first is a new type curve method that does not employ the well function as commonly done in standard type curve analysis. Another is a new analytic method that takes advantage of the decreasing features of aquifer drawdown during the intermediate pumping stage. We have demonstrated the applicability and robustness of the two new graphical methods for aquifer characterization through a synthetic pumping test.  相似文献   

Ordovician integrative stratigraphy and timescale of China     

Zhang  Yuandong  Zhan  Renbin  Zhen  Yongyi  Wang  Zhihao  Yuan  Wenwei  Fang  Xiang  Ma  Xuan  Zhang  Junpeng 《中国科学:地球科学(英文版)》2019,62(1):61-88

In this chapter, starting with a brief review of the research history and current status in the studies of the Ordovician chronostratigraphy in China, the subdivision of the Ordovician System, definition and recognition of its series and stage boundaries, and possible stratigraphic gaps are discussed in details in order to establish a multidisciplinary stratigraphic correlation through an integrated approach including lithostratigraphy, biostratigraphy, radiometric dating, chemostratigraphy and magnetostratigraphy. Being internationally accepted, the Ordovician System is now subdivided into three series and seven stages, in ascending order, Lower(Tremadocian, Floian), Middle(Dapingian, Darriwilian) and Upper series(Sandbian, Katian,Hirnantian). Three of the seven "Golden Spikes" defining the bases of the Ordovician stages, which were established in 1997–2007, are located in China. As a regionally applied chronostratigraphy, the Ordovician System was subdivided in China into Lower(Xinchangian, Yiyangian), Middle(Dapingian, Darriwilian) and Upper series(Neichiashanian, Chientangkiangian,Hirnantian). This scheme agrees largely with the standard international classification, which can actually be directly applied to China, except for some special circumstances where the Neichiashanian and Chientangkiangian stages of the Upper Ordovician are used. Based on the new studies in recent years and distinctions and differences recognized in the development of the Ordovician System in the constituent terranes of China, a new framework for correlation among the major Chinese palaeoplates or terranes, e.g. South China, North China(including Tarim and Qaidam) and Xizang(Tibet)-western Yunnan, has been established. However, it has been recognized herein that uncertainties still remain on defining the base of the Tremadocian,Dapingian and Katian, and on the correlation between different mega-facies. More specifically, for the Tremadocian, the precise correlation of its base will depend on the better-defined conodont taxonomy, while for the Dapingian and Katian, on the correlation between different mega-facies. It is worthwhile to note that the chemostratigraphic studies of the Ordovician System in China produced the carbonate δ13 C curves for the Darriwilian(Middle Ordovician) and Katian(Upper Ordovician), which show significant differences from the composite global curve. Record of the Ordovician isotopic dating is relatively rare in China, with only three reliable ages from zircons that are all from the upper Katian to Hirnantian of the Upper Ordovician.Abundant bentonite beds in the Upper Ordovician of South China will also provide unique opportunities to advance the isotopic dating and related researches. Studies on the Ordovician magnetostratigraphy need to be significantly enhanced in China, as currently all the available results are restricted to the Lower Ordovician of North China, although they can be correlated with those known from other parts of the world. The analysis of the durational unevenness of the seven stages in the Ordovician supports the possibility to further subdivide the long-durational Tremadocian, Darriwilian and Katian stages, each into two substages.  相似文献   

A review of fully coupled atmosphere-hydrology simulations     

Ning  Like  Zhan  Chesheng  Luo  Yong  Wang  Yueling  Liu  Liangmeizi 《地理学报(英文版)》2019,29(3):465-479

Journal of Geographical Sciences - The terrestrial hydrological process is an essential but weak link in global/regional climate models. In this paper, the development status, research hotspots and...  相似文献   

Assessment of Geothermal Resources in Petroliferous Basins in China     

Wang  Shejiao  Hu  Junwen  Yan  Jiahong  Li  Feng  Chen  Ningsheng  Tang  Qi  Guo  Bincheng  Zhan  Lufeng 《Mathematical Geosciences》2019,51(3):271-293

Mathematical Geosciences - In order to speed up the development and utilization of hydrothermal energy, it is essential to assess the potential of geothermal resources in petroliferous basins. In...  相似文献   

Dynamic analysis of slab track on multi-layered transversely isotropic saturated soils subjected to train loads   总被引：1，自引：0，他引：1  

Zhan Yongxiang  Yao Hailin  Lu Zheng  Yu Dongming 《地震工程与工程振动(英文版)》2014,(4)

The dynamic responses of a slab track on transversely isotropic saturated soils subjected to moving train loads are investigated by a semi-analytical approach. The track model is described as an upper Euler beam to simulate the rails and a lower Euler beam to model the slab. Rail pads between the rails and slab are represented by a continuous layer of springs and dashpots. A series of point loads are formulated to describe the moving train loads. The governing equations of track-ground systems are solved using the double Fourier transform, and the dynamic responses in the time domain are obtained by the inverse Fourier transform. The results show that a train load with high velocity will generate a larger response in transversely isotropic saturated soil than the lower velocity load, and special attention should be paid on the pore pressure in the vicinity of the ground surface. The anisotropic parameters of a surface soil layer will have greater influence on the displacement and excess pore water pressure than those of the subsoil layer. The traditional design method taking ground soil as homogeneous isotropic soil is unsafe for the case of RE 1 and RG 1, so a transversely isotropic foundation model is of great significance to the design for high train velocities.  相似文献   

基于DFP算法的小尺度微震定位方法研究     

崔仁胜  陈阳  王洪体  陈翰林  李江  林湛  周银兴 《震灾防御技术》2014,9(S1):639-647

针对小尺度微震活动监测的需要，本文基于DFP优化算法以传感器监测到时和计算到时的残差平方和最小为目标函数来进行微震震源位置定位，并对该方法进行了计算机数值仿真。仿真结果表明，DFP算法可用来进行地震定位，其定位结果受计算初值影响较小，而受走时误差和波速误差影响较大。通过野外微震观测实验研究，证明DFP法定位精度较高，适用于小尺度微震活动定位分析。  相似文献   

Generalized diffraction‐stack migration and filtering of coherent noise     

Ge Zhan  Wei Dai  Min Zhou  Yi Luo  Gerard T. Schuster 《Geophysical Prospecting》2014,62(3):427-442

We reformulate the equation of reverse‐time migration so that it can be interpreted as summing data along a series of hyperbola‐like curves, each one representing a different type of event such as a reflection or multiple. This is a generalization of the familiar diffraction‐stack migration algorithm where the migration image at a point is computed by the sum of trace amplitudes along an appropriate hyperbola‐like curve. Instead of summing along the curve associated with the primary reflection, the sum is over all scattering events and so this method is named generalized diffraction‐stack migration. This formulation leads to filters that can be applied to the generalized diffraction‐stack migration operator to mitigate coherent migration artefacts due to, e.g., crosstalk and aliasing. Results with both synthetic and field data show that generalized diffraction‐stack migration images have fewer artefacts than those computed by the standard reverse‐time migration algorithm. The main drawback is that generalized diffraction‐stack migration is much more memory intensive and I/O limited than the standard reverse‐time migration method.  相似文献   

中国地质学会2020年度“十大地质科技进展”   总被引：1，自引：0，他引：1  

中国地质学会 《地质论评》2021,67(2):6702339-6702366

大庆油田等:松辽盆地北部古龙页岩油勘探取得重大发现大庆油田在松辽盆地北部古龙凹陷青一段地层的纯页岩内实现水平井产量重大战略突破,试油获高产工业油气流,定产试采表现出稳定的高产能力,平面上15口直井试油证实古龙页岩油平面分布范围广,规模立体含油,轻质油带具有较好的产油能力,轻质油带页岩油气资源量达到几十亿吨。通过岩心精细描述及实验分析化验数据,建立了以古沉积环境控制原始优质烃源岩发育、适中的热演化程度控制油气富集。  相似文献